7at 4.08 FD Thoughts
 

Curious as to how much faster the car is with these on? Heard people say i lose top end and top speed, heard others say its the best mod to go faster if you are N/A. Is it worth it? Any thoughts and opinions are appreciated.

No, too much rear gear ratio for 1'st and maybe 2'nd.

Unless your running a pro stock racer at the track, your better off running a 3.7 gear for the street. (my setup)

No more than 10% additional gear ratio for a streetable upgrade, unless you race and then its a whole new set of calculation criteria. Then, if your forced induction, well that's a whole new ballgame lol

I swapped the 3.36 for the 3.7 in my G37, it was by far the best mod I did and the only thing I lacked for full bolt was headers. ( To include a PST carbon driveshaft with aluminum U's) . I did drop 5mph on top speed and had to have the speed sensor code turned off in uprev and lost cruise control. I did a simple pumpkin swap from a 6MT to my car and paid under 400 shipped on ebay. Took about two hours to install in the garage using two jacks and stands. ( One jack dedicated to the pumpkin because that bastard is a beast. ) 4.08 gives a bit better accelleration at the expense of traction. Another option is 3.9 but if you can locate a 6MT pumpkin instead I'd just go the way of 3.7 and enjoy.

:iagree: I did a bunch of gear calculations when trying to decided myself & 1st spooled up too fast. You won't lose any top end in real life & in-fact probably gain top end. I also run the 3.69's & am happy with the choice. The gearing difference for an auto going from 3.32 to 3.69's (10.03% ) is more than a manual going from 3.69's to 4.08's (9.6%) ;)

i have the 4.08s
the car just goes a bat out of hell
i aslo have a modified torgue converter
check out the 1/4 mile time and trap with only bolt ons
have big tires 305 35 18 MT

I have 4.08s in my car and they are worth every penny. Best mod I have done on the car. I actually wrote a review, you can check it out in the link below. As far as top speed goes, you probably will not notice a difference unless your planning on going over 180MPH.
http://www.the370z.com/engine-drivet...ml#post2051389

Anyone ever done the new nismo 3.9 ratio in an auto?

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I have no problems with 4.08s and full bolt-ons. The question is how will it work with a vortech SC? Power ramps up more gradually so maybe it will be okay. I doubt it'd get any traction with TT.

Unsure how many bolt on’s You have; I added 40rwhp with exhaust,CAI & Tune....added a few more smaller things-but not retuned yet.
Hot weather w/345/30’s on 12” Wheels- traction is good.
Cold weather/ not good...I did lose acceleration with additional 48lbs. Of rotating mass from Wheels.
Drop in 3.69 Nismo diff & gained acceleration back & bad traction issues in 1,2nd. 3rd gear 45 up Rollin or higher (in cool weather)
I hit rev limiter @116mph (7700) in 4th gear w/worn 345/30’s (26.8”)
I’m sure they will hook fine at the Dragstrip.
As mentioned earlier....rpms up 250 @75mph cruise.
3.90 would add another 150 & another 150 for 4.08’s.
Unsure your goals/ but won’t matter much on tire size,,, as the 4.92 & 3.19 1st,2nd gear ratios will blister up some rubber.
Will be fun to drive.
I’m about to install factory diameter/width tire’s on base Wheels- so this could be interesting.
Right now: A 60roll is neck snapping.
Repost what you do. :)

Nope; but I’d like to get one...actually a 3.92:1

Searching back in the 3.69 review I found this on the 3.9's. I had also thought about going 3.9's but the cost to wow factor over the 3.69's I already had didn't add up to me. To be honest I keep entertaining the idea of going 4.08's as the car is just a toy I rarely drive,even though the 3.69's are doing nicely. It's always the quest for more even though the car will already break traction just fine. :cool:



Here are 2 reviews with 3.69's & 4.08's with the Auto:

http://www.the370z.com/engine-drivet...ar-review.html

http://www.the370z.com/engine-drivet...at-review.html

Hey I have 4.08 with bearing and seals for sale ;) brand new

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I saw that ;)